Modulation of neuromuscular excitability in response to acute noxious heat exposure has no additional effects on central and peripheral fatigability.

Whole-body hyperthermia (WBH) has an adverse effect on the nervous system and neurophysiological performance. In the present study, we examined whether short-duration whole-body immersion in 45°C water (HWI-45°C), which produces a strong neural and temperature flux without inducing WBH, can increase or impair neurophysiological performance in humans. Fifteen men (aged 25 ± 6 years) were enrolled in this study and participated in three experiments: 1) a brief (5-min) immersion of the whole body in 37°C water (WI-37°C); 2) a brief (5-min) HWI-45°C; and 3) a control trial in a thermoneutral condition at an ambient temperature of 24°C and 60% relative humidity.

Exposure to acute noxious heat evokes a cardiorespiratory shock response in humans.

Noxious acute cold stimuli cause cold shock the sympathetic nervous system. However, no studies have investigated respiratory "heat shock" in response to noxious acute heat stimuli (≥ 42 °C). In the present study, we examined whether short-duration whole-body immersion (for 5 min) in noxious hot water (45 °C) is a sufficient stimulus to induce a respiratory acute shock response.